<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>动画实现步骤</title>
  <style>
    .box {
      width: 200px;
      height: 100px;
      background-color: pink;

      /* animation: changeSize 1s; */
      animation: changeStatus 1s;
    }

    /* 动画一: 宽度从200变化到800 */
    @keyframes changeSize {
      from {
        width: 200px;
      }
      to {
        width: 800px;
      }
    }

    /* 动画二: 从200*100变化到300*300变化到800*500 */
    @keyframes changeStatus {
      /* 百分比是指动画时长的百分比 */
      0% {
        width: 200px;
        height: 100px;
      }
      20% {
        width: 300px;
        height: 300px;
      }
      100% {
        width: 800px;
        height: 500px;
      }
    }

  </style>
</head>
<body>
  <div class="box"></div>
</body>
</html>